Austria's foreign ministry has been targeted by a "serious cyber attack", officials said, warning another country could be responsible.
The attack, which began Saturday, was continuing on Sunday and "experts say it could last several days," a foreign ministry spokesman told AFP.
The interior and foreign ministries issued a statement about the attack which started shortly before 11.00 pm (2200 GMT) on Saturday.
"Due to the gravity and nature of the attack, it cannot be excluded that it is a targeted attack by a state actor," the statement said.
"In the past, other European countries have been the target of similar attacks. Immediate measures have been taken and a "coordination committee" set up, the statement said.